Picture posting is enabled for all :)
Ammonium sulphamate really does kill the stuff, but the EU banned it's use, because it refused to review the data supplied unless it contained details of animal testing on dogs, which the supplier thought would cause unnecessary suffering to animals You can only buy it to as a compost accelerant now.See https://en.wikipedia.org/wiki/Ammonium_sulfamate and other sites about it and its use.
of course the experienced allotmenteers on this forum would only take a couple of hours to dig 300 tonnes of soil but for newbies it would take perhaps a lifetime or a bit longer.